Dedicated wind farms are an increasingly important source of energy for data centers.

REDMOND, Wash. – Microsoft is kicking up its targets for environmentally sustainable cloud computing by pledging that half of the electricity to power its data centers will come from renewable sources by 2018.

The bar will be raised to 60 percent for the early 2020s. “And then we’ll just keep on getting better from there,” Brad Smith, Microsoft’s president and chief legal officer, told energy executives today at a gathering of the Renewable Energy Buyers Alliance, or REBA.

Smith’s announcement provided a timely kickoff for this week’s REBA Summit on the Microsoft campus in Redmond. More than 300 representatives of companies that produce, sell and buy electrical power are meeting to trade information, recap successes and failures, and make deals.

“Our data centers, for each company, consume as much electrical power as a small state,” Smith said at the summit. “And there is going to come a time in the future, some decades ahead, when each of these companies will consume as much electrical power as a medium-sized nation.”

Smith said Microsoft is already cleaning up its cloud. The company’s data centers have been 100 percent carbon-neutral for a couple of years – but that includes purchases of carbon credits, such as last year’s deal involving the Nisqually Carbon Project. Right now, only about 44 percent of the electricity used by the data centers comes from renewable sources, Smith said.

To raise that figure, Microsoft will focus on bringing new renewable energy sources online, through investments in new projects as well as by encouraging more availability of clean energy through existing avenues, including utility grids. Smith pledged that Microsoft would be more transparent about reporting its patterns of energy use, and more active in R&D aimed at making data centers more energy-efficient.

We are growing and adding load, and that allows us to do things that companies with stable load can’t.

Microsoft and Amazon both came in for criticism last year in a controversial report from Greenpeace about data-center energy consumption. In Microsoft’s case, Greenpeace said the company’s reliance on renewable energy credits was a “wrong turn.”

Today, Smith made clear that Microsoft’s goal was to get 100 percent of its power from renewable sources, rather than relying on accounting to achieve carbon neutrality. “Anytime we purchase green energy, we will not sell the renewable energy certificates or any other green ‘attributes’ for others to claim,” he said in a blog post timed to coincide with the REBA Summit.

The other top cloud companies are settling on similar goals. Amazon, for example, aims to get 40 percent of the electricity for its global infrastructure from renewable energy sources by the end of 2016. That’s a significant improvement over the 25 percent figure from a year ago.

Facebook reached the 35 percent level last year and is targeting 50 percent for 2018, said Bill Weihl, director of sustainability for the social-media giant. Google and Apple are around the 35 percent mark as well.

Dedicated solar and wind farms are an important part of the strategy for going 100 percent renewable. Amazon, for example, is setting up wind farms in Indiana, North Carolina and Ohio, as well as a solar farm in Virginia. Those facilities are expected to deliver enough energy to power the equivalent of 150,000 U.S. homes annually.

Weihl explained that the rise of the cloud has given tech companies more clout with power providers. “We are growing and adding load, and that allows us to do things that companies with stable load can’t,” he told GeekWire.

The companies behind the cloud may compete fiercely for business, but when it comes to getting the energy for the cloud, they’re collaborators rather than competitors, Weihl said.

“It’s an unbelievably collaborative effort,” he said. “Microsoft is all in. Amazon is in, and pushing hard. Google is in.”

And based on the room-filling turnout for this week’s REBA Summit, a lot of other companies are in as well.